A number of epidemiologic studies indicate an association between air pollution as measured by sulfur dioxide (SO2) and total suspended particulates (TSP) and health. SO2 alone is considered to be of relatively low toxicity, but in the presence of TSP or ozone, or after conversion to particulate sulfate or sulfuric acid, it is believed to become a major contributor to adverse health effects. The CHESS studies provide some support for the viewpoint that acid sulfates and sulfuric acid may be more important pollutants than SO2 in terms of health consequences. The main objective of this study is to investigate the impact of air pollution, as measured by SO2 and TSP and sulfates, on human health. The study region was chosen to be Allegheny County, located in $ Southwestern Pennsylvania, having a long history of air pollution. A diffusion model will be used to divide the county into two regions having different pollution levels. A methodology will be developed to determine daily air pollution variates for a large region from the air pollution measurements obtained from monitoring stations and meteorological observations. Air pollution variates, after being adjusted for weather variates, trend and seasonal variations, will be related to mortality and morbidity variates through a mathematical model from which excess mortality and morbidity attributable to pollution will be estimated. A comparison of this excess mortality and morbidity between the two regions having different pollution levels will provide information as to the relative importance of SO2, TSP and sulfates in producing adverse health effects.